Design of a circularly polarized microstrip array mounted on a cylindrical surface

Microstrip antennas are very well suited to conformal array applications. Mounted on cylindrical surfaces, most of the developments emphasize the design of N-element wraparound arrays for omnidirectional radiation in the cylindrical roll planes. This paper reports the design of a circularly polarized (CP) circumferential array for the SONDA IV, a Brazilian sounding rocket. Using an effective home made CAD tool (Cylindrical), the minimum number of radiating elements needed to obtain a radiation characteristic as close as possible to an isotropic pattern was determined. Then, constructive details were taken into account in order to finally define the total number of antennas. To validate our assumptions and the design procedure, a prototype of a sub-array of four CP microstrip patches was manufactured, and the tests results show very good agreement with the simulations.